JEE Main Physics question

If the kinetic energy of a body is directly proportional to time t, the magnitude of the force acting on the body is

Answer: (B),(D)

Solution

K ∝ t ⟹ v² ∝ t ⟹ v ∝ √t. F = m(dv/dt) ∝ d(√t)/dt ∝ 1/√t, so F is inversely proportional to √t — (B) is

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Question ID VK-153794